In this proposal we seek to demonstrate a new experimental approach to develop a new subtractive method to remove abundant proteins from complex human fluid samples. The ultimate goal is to develop a suite of methods or tools to facilitate the de novo discovery of a complete set of low-abundance potential protein biomarkers from which more targeted studies can be performed. A particular interest is in the discovery of potential biomarkers for cancers, and in the past we have studied lung cancer samples and references drawn from the same cohort. In this Phase I proposal, we seek to demonstrate the selective and specific removal of human serum albumin isoforms and dimers from human plasma. These serum albumins comprise half of the protein in human serum or plasma, and cause very real issues with both tandem mass spectrometry and difference gel electrophoresis approaches. The Phase II would extend to work to remove three orders of magnitude of abundant proteins, a 50 times increase from existing state-of-the-art methods. One key feature is that the conditions are chosen to minimize protein-protein interactions, which compromise the performance of existing methods. The simplified human fluid samples produced will be compatible with both 2D gel electrophoresis and liquid chromatography- tandem mass spectrometry approaches.